Traumatic brain injury (TBI), often referred to as the silent epidemic, is an important health problem that disproportionately affects older adults. Older adults also are disproportionately affected by the need for anticoagulation (AC) medications since these medications are given to prevent thromboembolism in patients with conditions such as atrial fibrillation, prosthetic heart valves, deep vein thrombosis, and ischemic stroke, which are especially prevalent among older adults. Thus, it is not surprising that many older patients presenting with TBI were taking AC medication at the time of their brain injury. The co-occurrence of TBI with the need for AC therapy poses a serious clinical dilemma: Should AC therapy be resumed after a TBI, and if so, when? Current clinical guidelines do not provide guidance regarding the safety or timing of resumption of AC therapy after traumatic events in general, or specifically after TBI in older adults. The objectives of this application are to characterize practice patterns related to resumption of AC medication after a TBI and to quantify the impact of post-TBI resumption of AC medication on outcomes in older adults. Our rationale is that resumption of AC therapy after a TBI is associated with competing beneficial and adverse outcomes, and there is a paucity of information about quantification of the benefit-risk ratio. To achieve the study objectives, we propose two study aims using a retrospective cohort design and incorporating state-of-the art statistical methods to analyze Medicare administrative data: 1) To identify factors associated with time to resumption of anticoagulation therapy among Medicare beneficiaries who were receiving long-term AC therapy at the time of a TBI episode; and 2) To evaluate the balance of beneficial outcomes (prevention of thromboembolism) and adverse outcomes (hemorrhage) associated with early resumption, delayed resumption, or no resumption of AC therapy after a TBI. This proposed work is innovative because it capitalizes on our unique experience and access to the Medicare Part D drug data to answer an important clinical question with the potential to significantly improve outcomes following serious injury in older adults. The expected outcomes of the proposed study are increased knowledge about current real world practice patterns, using a nationally representative database, and the benefits and risks of resumption of AC medication post-TBI. The results of this study will support creation of evidence-based guidelines for improving the management of the increasing problem of TBI in older adults, especially those with coexisting conditions that require anticoagulation. I addition, the results will inform the design of future multicenter randomized controlled trials tha study the impact of resumption of AC following TBI in older adults.